Modern BVR Air Combat : Tactics, Effectiveness & Myths

Modern BVR Air Combat : Tactics, Effectiveness & Myths
Beyond Visual Range (BVR) Air Combat has been a topic filled with misunderstandings, myths, and scanty information, largely owing to a lack of credible information available to the general public. In this thread, I will try to explain BVR air combat in simple words possible, and then gradually go higher.

It has been to my observation, after 27 Feb Indo-Pak Air Skirmish, fanboys, journalists, and even veteran defense personnel making inaccurate observations/claims regarding air combat, missiles, and tactics. This has been one of my motivations to churn out these articles.

As I was writing the article, I realized I have much more content to share, hence I will span this article in multiple parts, and I will update them weekly.

Infomation Disclaimer - The knowledge presented here is gathered from numerous online & offline sources over the year by the author, and hence citing them is not in scope. Authenticity, correctness or consistency of the information presented is not guaranteed, and readers may accept them upon their own discretion

Image Disclaimer - All the images in this post are sourced from Google, and the author does not claim to own any of the image
Part 1: BVR Air Combat Terminologies

It is important to understand the basics of air combat and terminologies before going into the nitty-gritty. Also, many of you may have your existing knowledge challenged, hence I strongly advise skim through them.

By bookish definition, beyond visual range (BVR) combat is termed as any engagement (with missiles) beyond 37 km (20 nautical miles). However, this term means exactly what it says, any air to air missile launched from beyond a pilot's visual identification range.

There are mainly three types of BVR missiles currently in service around the world. namely -
  1. Semi-Active Radar Guided Missile :- Launching aircraft "illuminates" the target with its radar, and the missile's onboard seeker "listens" to radar waves reflected back from the target aircraft to guide itself.

    Let's take an example of a hunter (Launching aircraft) catching a rabbit (Target enemy aircraft) with his dog (Missile) at night. The dog cannot see the rabbit in darkness, so the hunter takes out his flashlight and shines it on the rabbit. The dog then runs towards the rabbit to catch it. The hunter has to keep its flashlight focused upon the rabbit till the dog catches it, otherwise, it will be lost in darkness.
    The advantages of this kind of missile are their simplicity, and hence cost-effectiveness. Packing a passive-sensor at the nose of the missile is much easier and cheaper than housing an active radar seeker (below mentioned). Passive seeker also allows them to be accurate at very-long ranges, as closer the missile reaches the target aircraft, the reflected radar signal becomes stronger.
    However, the biggest disadvantage of such missiles is, the launching aircraft will have to keep illuminating the target aircraft till the missile hits it. Such missiles are not "fire and forget".

    Examples of Semi-Active Radar Guided Missile:-

    American AIM-7 Sparrow
    avspaam_04.jpg


    Soviet R-27 (R & ER versions) "Alamo" -
    r27.jpg


    French Matra Super 530D -
    MatraSuperR530_01.jpg



  2. Active Radar Guided Missile :- Missile has its own radar transmitter and receiver, which can now guide the missile with minimal assistance of launching aircraft. Again, let's take our example of the hunter.

    The hunting dog (missile) has its own small flashlight using which it can now see the rabbit (target enemy aircraft). The hunter (launching aircraft) has its own powerful flashlight, he points his flashlight towards the rabbit, and let his dog loose. Now since the dog can use his own small flashlight to see the rabbit in darkness, there is no need of hunter to keep his flashlight focused on the rabbit.
    But, it is to be noted that the radar transmitter of the missile is proportionally quite small and less powered than launching an aircraft's radar. Hence, the missile can only accurately "see" & track targets at much lower distances. Active-radar guided missiles have a clear advantage over Semi-Active radar-guided missiles that are "fire and forget" (or is it?), at least theoretically. Since the active radar on the missile has a limited range (~around 30 km detection), the launching aircraft has to guide it till the missile is close enough to use its onboard active radar to track the target aircraft.

    Examples of active-radar guided missiles -

    American AIM-120 AMRAAM -
    amraam.jpg


    Russian R-77 "Adder" -
    r77.jpg


    Chinese SD-10, also known as PL-12 -
    sd 10.png



  3. IR/Heat Seeking Missile :- Heat-seeking missiles, in general, have an infrared/electro-optical camera in front of the missile. This camera can "see" low-spectrum lights, a.k.a dissipating heat waves emitted from any object. Since jet aircraft, fortunately, have hot-air exhausts (jet exhaust) at their behind, they are quite easily spotted from background clutter. Moreover, at high speeds, the friction of air with the skin of the aircraft itself produces heat.

    The hunting dog (missile) now has night vision goggles! But the range of night vision goggles is not much, hence the hunter (launching aircraft) may still have to guide the dog to the rabbit (target enemy aircraft) close enough till the dog can use its own night vision goggles to "see" the rabbit
    Great! The only problem is, the visual range of such cameras tends to be not much. Hence, again, the launching aircraft often has to guide the missile close enough to the target aircraft so that the infrared sensor/camera of the missile can "see" the target aircraft.
    The greatest advantage of IR/Heat-seeking missiles is their "passiveness", that is, the missile emits/transmits no radar signal, detecting an incoming IR/Heat-seeking missile is extremely difficult.

    Examples of IR/Heat Seeking BVR Missiles -

    Russian R-27 (T & ET versions) "Alamo" -
    r27et.jpg


    French MICA IR -
    micair.jpg



    Notice, I have not mentioned the range of any of the missiles, which brings us to the next part, defining the range of a BVR missile. This has been a much-convoluted topic, and naturally, quite misunderstood. By range of the missile, we generally understand the maximum range of the missile at which it can successfully kill the target, however, there is also something as a minimum range of a missile. Let's understand both of them.
  • Maximum range of BVR missile :- One of the reasons why the maximum range of a missile is complicated, is because it is affected by multiple factors. A quote of "x" kilometers means very little, and often such "maximum" kill ranges are ideal launch cases experimented in favorable conditions. Let's look at factors affecting a missile's kinematic performance & also kill probability.
    • Speed of launching aircraft - Missile launched at higher speed attain greater range. Both of their velocities add up.

    • The density of air (or altitude of launch) - Higher density of air (low altitude) exhibits more drag upon the missile, slowing it down. However, very low-density air (very high altitude) will have a counter-effect of not providing enough reaction force for the thrust coming out of missile.

    • Aerodynamics & control-surfaces on the missile - Larger control surfaces increase air drag, slowing the missile down.
  • Minimum range of BVR missile :- Minimum range means the least amount of distance the enemy adversary needs to be away from launching aircraft for the missile to be effective. Well, why is that so?
    • BVR missiles often have smaller fins than short-range engagement missiles, hence they need to achieve a minimum airspeed before their fins can be used to control missile's direction.
      aim9aim120.jpg

      AIM-9M Sidewinder short-range heat-seeking missile vs. AIM-120 AMRAAM. Both use their fins for directional control, notice the difference in their fin size & area comparative to missile body.

    • Just out of the rail, BVR missiles often lack the maneuverability of short-range missiles and hence are more probable to miss their targets.

    • BVR missiles (especially Active-Radar Guided) seeker need to "lock-on" upon the target aircraft to guide itself. The missile lock on target is after launch (Lock-on-after-Launch), hence it needs some time for seeker & electronics to properly determine and lock upon the target.
Okay, now that we understand the types of missiles and the launch parameters upon which they are effective, let's look at what are the propulsion types.
Although there are many other types of propulsion used in normal missiles, in context of BVR missiles, we are gonna talk about below three -
  • Solid Fueled Rocket Motor (Single Stage) - The most common type of propulsion in BVR missiles, owing to their simplicity, compact nature, minimal to no moving parts and providing high specific impulse, or in simpler terms, how much thrust the rocket engine provides per unit of propellant.

    Solid fueled rockets require no air/oxygen to burn their propellant. A simple solid-fueled rocket’s example is a rocket firework often used during New Year or Diwali celebration.
    solidfuel.gif


    Advantages of Solid Fueled Rocket Motor is its simplicity, efficiency, low cost, and low maintenance while retaining excellent performance characteristics. However, there exists no throttle on solid-fueled rockets, and as they start burning, they stop only after the whole propellant is empty. This makes missiles to achieve a very high speed off the rail, and after the propellant burns out (which is like 4-8 seconds after launch for most missiles), the missile just glides the remaining distance to the target after that.

    Let’s say I am on a bicycle (missile) chasing a thief (enemy aircraft). My bicycle has no pedal, so my friend(solid rocket motor) gives my bicycle an initial push forward for a few seconds to get me on speed. Now the rest of the chase I just steer my handle till I reach the running thief.
    The disadvantage of such propulsion is evident. The flying missile keeps on losing speed after the rocket motor runs out. And if the enemy jets make complex maneuvers which the missile also has to follow, the missile can easily lose its momentum and just fall down like a rock.

    We will read about that more BVR missile evasion tactics later.

  • Dual Pulse Solid Rocket Motor (Dual Stage) - The core engine is the same, Solid rocket motor, however, there are two of them now. To negate the disadvantage of losing speed (after the rocket motor has finished burning) while chasing the foe, why not have another rocket motor to give it speed and propulsion during the chase?

    Now after I reach near the running thief (enemy aircraft), I call my friend(second rocket motor) to give another round of push to my bicycle (of course for a few seconds only). Now my chances of catching the running thief are more as his left-right dashes or running in the opposite direction will not make my bicycle loose speed.
    This, however, makes the missile bulky, longer, and more costly, but it is often worth the cost.

  • Ramjet Powered (Air-Breathing Engine) - The idea of giving missiles some kind of internal combustion engine to improve its range and flight characteristics are not new, as most of the cruise missiles and long-range anti-ship missiles have such engines. However, typical jet engines like turbojet/turbofan engines cannot provide enough power to air-to-air missiles to reach high speeds necessary to chase enemy aircraft down.
    One solution is to use Ramjet/Scramjet engines, which although only work at higher speeds, are able to provide enough power to propel the missile to high Mach numbers. It is also to be noted, Ramjet/Scramjet engines are not fully mastered owing to their strict working parameters and requirements of high heat-tolerant materials.

    Still, such engines are being looked into as prospective propulsion systems for next-generation air-to-air missiles. Ramjet/Scramjet powered air-to-air missiles need an initial booster (typically a solid-fueled rocket motor) to propel the missile to initial fast speeds so that the Ramjet/Scramjet engine can start.

    Now I can pedal my bicycle(missile) to catch the thief(enemy aircraft), however, I still need help from my friend(rocket motor booster) to push me for a few seconds so that I can activate my peddling (bad peddle design!). After my friend has pushed me for a few seconds, I start pedaling to reach the running thief, since I got my own propulsion, chances of me losing speed while catching the thief is minimal.
    Advantages of ramjet/scramjet-powered air-to-air missiles are its excellent flight characteristics, extreme-long ranges thanks to the efficient propulsion system and high kill probability due to high terminal chase speed.
    However, such missiles tend to be very costly, and few of the countries actually have the technical expertise to design and manufacture such a missile.


    MBDA Meteor is the only operational BVR to have Ramjet-powered propulsion.


  • [Bonus] Clean-Burning Fuel vs. Smoky Fuel - This is one of the most critical aspects of a missile that people often overlook. Clean-burning fuel makes no contrails/residual smoke plume behind the missile, whereas smoky fueled missiles often leave a smoke-trail similar to high-flying jets/airlines created in the sky.

    Clean-burning fuel missiles have a significant advantage as their visual signature is practically nil, whereas a smoky fueled missile is visible (by its smoke trail) as far as 30 kilometers away or even more on a clear day. Passive missile (like IR/IIR) launch can only be detected visually (or with MAWS, we will come back to it later) and if the pilot fails to spot them visually, it's practically game over for them.


    The clean-burning propellant of Astra leaves a very minimal visual signature.


    Smoky propellant of R-27 leaves a very distinct trail against a clear sky.

    Now let's look at one important aspect of the missile, its warhead/payload. Air-to-air missile warheads are special in the sense that they are designed to “kill” or “disable” other aircraft.

    When designing a warhead that “kills” an aerial vehicle, the first observation is that aircraft are very soft-bodied, typically made of thin sheets of aluminum alloys, or composites to reduce weight. Also combined with the fact that aircraft are practically jam-packed with critical electronics, hydraulics, and actuators, they are pretty vulnerable towards even small explosives and shrapnel damage.
    Unsurprisingly, missile warheads are generally fragmentation-type, which can shred the aircraft and its critical components. Let’s look at some popular warhead types -

  • Blast Fragmentation / Annular Blast Fragmentation - Such kind of warheads typically have an explosive surrounded by fragmentation (generally shaped steel pieces/balls). The explosion creates a donut-shaped cloud of shrapnel that shreds anything around it.


    Donut-shaped blast cloud of AIM-120 AMRAAM warhead detonation.

  • Continuous-Rod Warhead - One of the infamous warheads that practically “cuts” the target aircraft in half by its expanding ring of rods. The warhead is surrounded by rods welded at every second consecutive end. When the warhead explodes, the rod expands to become a big-hot loop, which cuts the aircraft in half.


    Visual-depiction of the continuous-rod warhead in action

    Now that we have mostly covered the important terminologies of a missile, now let’s look at terminologies about detecting and evading the BVR missile.

  • Radar Warning Receiver (RWR) :- This system is used to detect and interpret the radar signals. Typically fitted in, but not limited to, combat aircraft to detect threat radar signals and take effective action. This system is an integral part of modern combat, as RWRs can detect, classify, and take necessary action against the type of threat interpreted.

    Remember the Hunter-Dog-Rabbit example? Let’s go through that again.
    Let's say Rabbit (target aircraft) knows the flashlight’s color of hunters(launching aircraft) and dogs (air-to-air missile). Now whenever an unknown hunter flashes its flashlight in the dark to find the rabbit, the rabbit instantly knows who is the hunter(the identity of aircraft), and can take necessary action (will talk about it later!)
    Most modern RWRs have directional and threat classification ability, that means it can detect from which direction the radar signal is coming, and what kind of unit (ground radar, SAM, enemy aircraft, friendly) is emitting that signal.
    It is to be noted that RWR is a passive system, and no signals are emitted from it to detect enemy radar signals.

  • Electronic Counter - Measures (ECM) :- Once the incoming threat has been detected, the threat radar can be spoofed/fooled in multiple ways. Two broad categories to fool an enemy radar are -
    • Interfere with the incoming radar waves and intending to provide false information to enemy radar (Jamming). Jamming is a very broad topic, hence let’s reserve it for some time next.

    • Create a decoy object around you to give incorrect information to enemy radar (Chaffs, decoys). Chaffs are small bits of aluminum, which when dispersed into the air, reflect radar-waves, giving false information about the size and the location of the target.


Finishing the terminologies part with these topics, I will update them if required.
The next part will be BVR Tactics & their effectiveness.
 

Comments

Let me explain it by demonstrating force balance on x-axis (considering point body)

Capture.JPG


1. Rocket Thrust: Acts on the Positive X-Direction by Newton's Third Law. I feel it's not the point of dispute.
2. Skin Friction: It acts against the relative fluid velocity w.r.t the body over which fluid is flowing. In relative frame of reference, I can say that the fluid is flowing over the missile body with velocity of same magnitude as the missile speed but in opposite direction (i.e. Negative X-Direction). Therefore, the velocity of air is in negative X-direction; As the skin friction always act in opposite direction on the FLUID with respect to relative flow velocity hence the friction will act on Fluid in Positive X- direction and as a reaction force the same amount will act on Missile body in Negative X- direction. Skin friction is a tangential force acting on the surface of missile.
3. Form Drag:
Form drag is a result of pressure difference caused by disruption/boundary layer separation which results in drop in pressure at the downstream of fluid flow. In this case, It will act on the missile body in Negative X-Direction.
Form Drag acts on projected area (cross-section normal to the plane of motion) of the blunt body. Hence, the nose cone is pointed to reduce the form drag.

1588446186737.png

A simple force balance diagram of airfoil can show that the drag force always act in Negative direction of motion of flow on the Moving Object.

1588446207887.png


In fact if I remember correctly, you have pointed out difference in AMRAAM and AIM 9X in terms of Fin size just to explain the minimum range. Higher drag induced by Larger fins in AIM 9X will give it additional control to deflect it to higher angles w.r.t the aircraft upon launching (Also known as High Off-Bore Sight capability).

Hope my explanation will put this question to rest. Would like to hear your opinion in this regard.
 
Let me explain it by demonstrating force balance on x-axis (considering point body)

View attachment 46854

1. Rocket Thrust: Acts on the Positive X-Direction by Newton's Third Law. I feel it's not the point of dispute.
2. Skin Friction: It acts against the relative fluid velocity w.r.t the body over which fluid is flowing. In relative frame of reference, I can say that the fluid is flowing over the missile body with velocity of same magnitude as the missile speed but in opposite direction (i.e. Negative X-Direction). Therefore, the velocity of air is in negative X-direction; As the skin friction always act in opposite direction on the FLUID with respect to relative flow velocity hence the friction will act on Fluid in Positive X- direction and as a reaction force the same amount will act on Missile body in Negative X- direction. Skin friction is a tangential force acting on the surface of missile.
3. Form Drag:
Form drag is a result of pressure difference caused by disruption/boundary layer separation which results in drop in pressure at the downstream of fluid flow. In this case, It will act on the missile body in Negative X-Direction.
Form Drag acts on projected area (cross-section normal to the plane of motion) of the blunt body. Hence, the nose cone is pointed to reduce the form drag.

View attachment 46855
A simple force balance diagram of airfoil can show that the drag force always act in Negative direction of motion of flow on the Moving Object.

View attachment 46856

In fact if I remember correctly, you have pointed out difference in AMRAAM and AIM 9X in terms of Fin size just to explain the minimum range. Higher drag induced by Larger fins in AIM 9X will give it additional control to deflect it to higher angles w.r.t the aircraft upon launching (Also known as High Off-Bore Sight capability).

Hope my explanation will put this question to rest. Would like to hear your opinion in this regard.
2. Skin Friction: It acts against the relative fluid velocity w.r.t the body over which fluid is flowing. In relative frame of reference, I can say that the fluid is flowing over the missile body with velocity of same magnitude as the missile speed but in opposite direction (i.e. Negative X-Direction). Therefore, the velocity of air is in negative X-direction; As the skin friction always act in opposite direction on the FLUID with respect to relative flow velocity hence the friction will act on Fluid in Positive X- direction and as a reaction force the same amount will act on Missile body in Negative X- direction. Skin friction is a tangential force acting on the surface of missile.

3. Form Drag:
Form drag is a result of pressure difference caused by disruption/boundary layer separation which results in drop in pressure at the downstream of fluid flow. In this case, It will act on the missile body in Negative X-Direction.
Form Drag acts on projected area (cross-section normal to the plane of motion) of the blunt body. Hence, the nose cone is pointed to reduce the form drag.
True. agreed. In general, drag force is a parasitic force trying to stop the motion of a moving body. I believe I said the same thing in the article.

1. Rocket Thrust: Acts on the Positive X-Direction by Newton's Third Law. I feel it's not the point of dispute.
There are two parts for the force propelling the missile forward.
  1. Opposite reaction force due to thrust pushing the air behind the missile - This is dependent on the density of the air. Less dense air will provide a lesser opposite reaction.
    My statement in the article -
    However, very low-density air (very high altitude) will have a counter-effect of not providing enough reaction force for the thrust coming out of missile.
  2. Opposite force due to conservation of momentum - If I throw a rock in space, I will be pushed back to conserve the momentum of the system. This is independent of the density of air.
Let me know if you catch upon what I am trying to say.
 
True. agreed. In general, drag force is a parasitic force trying to stop the motion of a moving body. I believe I said the same thing in the article.



There are two parts for the force propelling the missile forward.
  1. Opposite reaction force due to thrust pushing the air behind the missile - This is dependent on the density of the air. Less dense air will provide a lesser opposite reaction.
    My statement in the article -


  2. Opposite force due to conservation of momentum - If I throw a rock in space, I will be pushed back to conserve the momentum of the system. This is independent of the density of air.
Let me know if you catch upon what I am trying to say.
I got your point. From physics part, it's true that the gases coming out from exhaust will get less resistance in thin air as compared to dense air hence the lower reaction force. But for design calculations, the magnitude of this forward thrust is so low that its not even considered.
(Force is subjected to density difference between exhaust gases and surrounding air). I was more worried about Drag part, which you have clarified, it always act in opposite direction.
 

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